• Tuberculosis and Respiratory Diseases
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• v.58 no.6
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• pp.590-599
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• 2005

Object : Cigarette smoking is a major cause of mucus hypersecretion, which is a pathophysiological feature of many inflammatory airway diseases. Mucins, which are an important part of the airway mucus, are synthesized from the Muc gene in airway epithelial cells. However, the signaling pathways for cigarette smoke-induced mucin synthesis are unknown. The aim of this study was to determine the signal pathway for smoking induced Muc5ac gene expression. Methods : A549 cells were cultured and transiently transfected with the Muc5ac promoter fragment. These cells were stimulated with 5% cigarette smoke extract (CSE) alone or with CSE after a pretreatment with various signal transduction pathway inhibitors (AG1478, PD98059 and SB203580). The Muc5ac promoter activity was examined using the luciferase reporter system, and the level of phosphorylated EGFR, ERK1/2, p38 MAPK and JNK were all examined using Western blot analysis. Muc5ac mRNA expression was also examined using reverse transcriptase polymerase chain reactions (RT-PCR). Results : 1. The peak level of luciferase activity of the Muc5ac promoter was observed at 5% concentration and after 3 hours of incubation with the CSE. The level of EGFR phosphorylation and the luciferase activity of the transfected cells caused by the CSE were significantly suppressed by AG1478 or PD98059 (P<0.01). 2. CSE phosphorylated ERK1/2 or p38 MAPK but not JNK. The Muc5ac mRNA expression level was increased by the CSE but that was suppressed by PD98059 or AG1478. 3. The CSE-induced phosphorylation of ERK1/2 was blocked by PD98059 and that of p38 MAPK was blocked by either PD98059 or SB203580. Either PD98059 or SB203580 suppressed the luciferase activity of the transfected cells (P<0.0001). Conclusion : The Muc5ac mRNA expression level was increased by the CSE. The increased CSE-induced transcriptional activity was mediated via EGF receptor activation, which led to ERK1/2 and p38 MAPK phosphorylation.

• Journal of Life Science
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• v.17 no.7 s.87
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• pp.889-895
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• 2007

A conventional kinesin, KIF5/kinesin-I, is composed of two kinesin heavy chains (KHCs) and two kinesin light chains (KLCs) and binds directly to microtubules. KIF5 motor mediates the transport of various membranous organelles, but the mechanism how they recognize and bind to a specific cargo has not yet been completely elucidated. Here, we used the yeast two-hybrid system to identify the neuronal protein(s) that interacts with the tetratricopeptide repeats (TRP) of KLCI and found a specific interaction with JNK/stress-activated protein kinase-associated protein 1 (JSAP1/JIPP3). The yeast two-hybrid assay demonstrated that the TRP 1,2 domain-containing region of KLCI mediated binding to the leucine zipper domain of JSAP1. JSAP1 also bound to the TRP region of lac2 but not to neuronal KIF5A, KIF5C and ubiquitous KIF5B in the yeast two-hybrid assay. In addition, these proteins showed specific interactions in the GST pull-down assay and by co-immunoprecipitation. KLCI and KIF5B interacted with GST-ISAP1 fusion proteins, but not with GST alone. An antibody to JSAPI specifically co-immunoprecipitated KIF5s associated with JSAP1 from mouse brain extracts. These results suggest that JSAP1, as KLC1 receptor, is involved in the KIF5 mediated transport.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.802-808
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• 2013

Here we tried to uncover the potential anti-lipogenic effect and the underlying mechanism of Phaseolus angularis seed in a cellular model of nonalcoholic fatty liver disease (NAFLD) induced in HepG2 cells. Ethanol extract of Phaseolus angularis seed (JSD) was prepared. HepG2 cells were incubated in palmitate containing media to induce intracellular lipid accumulation, and co-treated with JSD for 16 hrs before examine intracellular lipid content. In control group, the cells were not co-treated with JSD. We measured the effects of JSD on liver X receptor ${\alpha}$ ($LXR{\alpha}$) and sterol regulatory element-binding transcription factor-1c (SREBP-1c) expression, transcription level of lipogenic genes, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD-1), and AMP-activated protein kinase (AMPK) activation in HepG2 cells. JSD markedly reduced palmitate-induced intracellular lipid accumulation in HepG2 cells. JSD suppressed $LXR{\alpha}$/SREBP-1c expression, and SREBP-1c mediated induction of ACC, FAS, and SCD-1. Furthermore, JSD activated AMPK, which plays a major role in the control of hepatic lipid metabolism. Taken together, it is suggested that JSD has a potential to alleviate hepatic steatosis, at least in part, by suppressing $LXR{\alpha}$/SREBP-1c mediated induction of lipogenic genes. In addtion, the anti-lipogenic potential may be associated with activation of AMPK. Therefore, the Phaseolus angularis seed could be applied as a potential therapeutics for NAFLD with additional clinical studies.

• Journal of Life Science
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• v.33 no.12
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• pp.967-977
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• 2023

Rubus crataegifolius (RC) is a traditional Asian medicinal plant belonging to the Rosaceae family. The fruits of RC are known to prevent adult diseases through antioxidants. In this study, the effects of RC extract (RCex) on obesity and nonalcoholic fatty liver disease (NAFLD) were evaluated in animal models. Twenty-eight male C57BL/6J mice were induced to become obese for 8 weeks and then the extract was orally administered for 8 weeks. RCex reduced body weight, adipose tissue, liver weight. RCex improved biochemical biomarkers including lipid metabolism (alanine aminotransferase (ALT), aspartate aminotransferase (AST), plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol). The activation of AMP-activated protein kinase (AMPK) reduced the expression of adipogenesis genes (liver × receptor (LXR), sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthesis (FAS), acetyl-CoA carboxylase 1 (ACC1) and the effect of enhancing carnitine palmitoyltransferase (CPT) activity by RCex was verified. RCex also influence on plasma production of hormones (adiponectin & leptin) related on energy expenditure and metabolism. In addition, we confirmed that RCex improved glucose intolerance in HFD-induced obese rats. RCex was first demonstrated to have anti-obesity as well as anti-NAFLD effects by regulating fatty acid oxidation and fatty acid synthesis by phosphorylation of AMPK. This suggests that RCex could be a good supplement for the prevention of obesity and related NAFLD.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.521-527
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• 1998

An important property of the intestine is the ability to secrete fluid. The intestinal secretion is regulated by a number of substances including vasoactive intestinal peptide (VIP), ATP and different inflammatory mediators. One of the most important secretagogues is adenosine during inflammation. However, the controversy concerning the underlying mechanism of adenosine-stimulated $Cl^-$ secretion in intestinal epithelial cells still continues. To investigate the effect of adenosine on $Cl^-$ secretion and its underlying mechanism in the rabbit colon mucosa, we measured short circuit current ($I_{SC}$) under automatic voltage clamp with DVC-1000 in a modified Ussing chamber. Adenosine, when added to the basolateral side of the muocsa, increased $I_{SC}$ in a dose-dependent manner. The adenosine-stimulated $I_{SC}$ response was abolished when $Cl^-$ in the bath solution was replaced completely with gluconate. In addition, the $I_{SC}$ response was inhibited by a basolateral Na-K-Cl cotransporter blocker, bumetanide, and by apical $Cl^-$ channel blockers, dephenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), glibenclamide. Amiloride, an epithelial $Na^+$ channel blocker, and 4,4-diisothiocyanato-stilbene-2,2-disulphonate (DIDS), a $Ca^{2+}-activated$ $Cl^-$ channel blocker, had no effect. In the mucosa pre-stimulated with forskolin, adenosine did not show any additive effect, whereas carbachol resulted in a synergistic potentiation of the $I_{SC}$ response. The adenosine response was inhibited by 10 ${\mu}M$ H-89, an inhibitor of protein kinase A. These results suggest that the adenosine-stimulated $I_{SC}$ response is mediated by basolateral to apical $Cl^-$ secretion through a cAMP-dependent $Cl^-$ channel. The rank order of potencies of adenosine receptor agonists was $5'-(N-ethylcarboxamino)adenosine(NECA)＞N^6-(R-phenylisopropyl)adenosine(R-$ PIA)＞2-[p-(2-carbonylethyl)-phenyl-ethylamino]-5'-N-ethylcarboxaminoadenosine(CGS21680). From the above results, it can be concluded that adenosine interacts with the $A_{2b}$ adenosine receptor in the rabbit colon mucosa and a cAMP-dependent signalling mechanism underlies the stimulation of $Cl^-$ secretion.

• BMB Reports
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• v.49 no.2
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• pp.111-115
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• 2016

Caffeine has been proposed to have several beneficial effects on obesity and its related metabolic diseases; however, how caffeine affects adipocyte differentiation has not been elucidated. In this study, we demonstrated that caffeine suppressed 3T3-L1 adipocyte differentiation and inhibited the expression of CCAAT/enhancer binding protein (C/EBP)α and peroxisome proliferator-activated receptor (PPAR)γ, two main adipogenic transcription factors. Anti-adipogenic markers, such as preadipocyte secreted factor (Pref)-1 and Krüppel-like factor 2, remained to be expressed in the presence of caffeine. Furthermore, 3T3-L1 cells failed to undergo typical mitotic clonal expansion in the presence of caffeine. Investigation of hormonal signaling revealed that caffeine inhibited the activation of AKT and glycogen synthase kinase (GSK) 3 in a dose-dependent manner, but not extracellular signal-regulated kinase (ERK). Our data show that caffeine is an anti-adipogenic bioactive compound involved in the modulation of mitotic clonal expansion during adipocyte differentiation through the AKT/GSK3 pathway.

• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.25-32
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• 2016

Lichens have been known to possess multiple biological activities, including anti-proliferative and anti-inflammatory activities. Vascular cell adhesion molecule-1 (VCAM-1) may play a role in the development of atherosclerosis. Hence, VCAM-1 is a possible therapeutic target in the treatment of the inflammatory disease. However, the effect of lobaric acid on VCAM-1 has not yet been investigated and characterized. For this study, we examined the effect of lobaric acid on the inhibition of VCAM-1 in tumor necrosis factor-alpha (TNF-${\alpha}$)-stimulated mouse vascular smooth muscle cells. Western blot and ELISA showed that the increased expression of VCAM-1 by TNF-${\alpha}$ was significantly suppressed by the pre-treatment of lobaric acid ($0.1-10{\mu}g/ml$) for 2 h. Lobaric acid abrogated TNF-${\alpha}$-induced NF-${\kappa}B$ activity through preventing the degradation of $I{\kappa}B$ and phosphorylation of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and p38 mitogen activated protein (MAP) kinase. Lobaric acid also inhibited the expression of TNF-${\alpha}$ receptor 1 (TNF-R1). Overall, our results suggest that lobaric acid inhibited VCAM-1 expression through the inhibition of p38, ERK, JNK and NF-${\kappa}B$ signaling pathways, and downregulation of TNF-R1 expression. Therefore, it is implicated that lobaric acid may suppress inflammation by altering the physiology of the atherosclerotic lesion.

• Journal of Photoscience
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• v.9 no.2
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• pp.229-232
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• 2002

There are two distinct UV-responsive signaling pathways in UV-irradiated mammalian cells, i.e., the DNA damage-dependent and -independent pathways. The former occurs in nucleus and results in growth arrest and apoptosis via post-translational modification of p53. The latter is initiated by oxidative stress and/or by damages in cell membrane or cytoplasm, which activate signaling cascade through intracellular molecules including mitogen activated protein kinases (MAPK). In normal human fibroblastic cells, all of MAPK family members, extracellular signal-related kinases (ERK), c-Jun N-terminal kinases (JNK) and p38, were rapidly phosphorylated following UV-irradiation. ERK phosphorylation was suppressed by an inhibitor of receptor tyrosine kinases (RTK). As ERK usually responds to mitogenic stimuli from RTK ligands, UV-induced ERK phosphorylation may be linked to the proliferation of survived cells. In contrast, phosphorylation of JNK and p38, as well as apoptosis, were modulated by the level of UV-generated oxidative stress Therefore, JNK and p38 may take part in oxidative stress-mediated apoptosis. Phosphorylation of p53 at Ser and Thr residues are essential for stabilization and activation of p53. Among several sites reported, we confirmed phosphorylation at Ser-15 and Ser-392 after UV-irradiation. Both of these were inhibited by a phosphoinositide 3-kinase inhibitor, presumably due to the shutdown of signals from DNA damage to p53. Phosphorylation at Ser-392 was also sensitive to an antioxidant and a p38 inhibitor, suggesting that Ser-392 of p53 is one of the possible points where DNA damage-dependent and -independent apoptic signals merge. Thus, MAPK pathway links UV-induced intracellular signals to the nuclear responses and modifies DNA damage-dependent cellular outcome, resulting in the determination of cell death.

• Journal of Ginseng Research
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• v.41 no.3
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• pp.257-267
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• 2017

Background: Heat-processed ginseng, sun ginseng (SG), has been reported to have improved therapeutic properties compared with raw forms, such as increased antidiabetic, anti-inflammatory, and antihyperglycemic effects. The aim of this study was to investigate the antiobesity effects of SG through the suppression of cell differentiation and proliferation of mouse 3T3-L1 preadipocyte cells and the lipid accumulation in Caenorhabditis elegans. Methods: To investigate the effect of SG on adipocyte differentiation, levels of stained intracellular lipid droplets were quantified by measuring the oil red O signal in the lipid extracts of cells on differentiation Day 7. To study the effect of SG on fat accumulation in C. elegans, L4 stage worms were cultured on an Escherichia coli OP50 diet supplemented with $10{\mu}g/mL$ of SG, followed by Nile red staining. To determine the effect of SG on gene expression of lipid and glucose metabolism-regulation molecules, messenger RNA (mRNA) levels of genes were analyzed by real-time reverse transcription-polymerase chain reaction analysis. In addition, the phosphorylation of Akt was examined by Western blotting. Results: SG suppressed the differentiation of 3T3-L1 cells stimulated by a mixture of 3-isobutyl-1-methylxanthine, dexamethasone, and insulin (MDI), and inhibited the proliferation of adipocytes during differentiation. Treatment of C. elegans with SG showed reductions in lipid accumulation by Nile red staining, thus directly demonstrating an antiobesity effect for SG. Furthermore, SG treatment down-regulated mRNA and protein expression levels of peroxisome proliferator-activated receptor subtype ${\gamma}$ ($PPAR{\gamma}$) and CCAAT/enhancer-binding protein-alpha ($C/EBP{\alpha}$) and decreased the mRNA level of sterol regulatory element-binding protein 1c in MDI-treated adipocytes in a dose-dependent manner. In differentiated 3T3-L1 cells, mRNA expression levels of lipid metabolism-regulating factors, such as amplifying mouse fatty acid-binding protein 2, leptin, lipoprotein lipase, fatty acid transporter protein 1, fatty acid synthase, and 3-hydroxy-3-methylglutaryl coenzyme A reductase, were increased, whereas that of the lipolytic enzyme carnitine palmitoyltransferase-1 was decreased. Our data demonstrate that SG inversely regulated the expression of these genes in differentiated adipocytes. SG induced increases in the mRNA expression of glycolytic enzymes such as glucokinase and pyruvate kinase, and a decrease in the mRNA level of the glycogenic enzyme phosphoenol pyruvate carboxylase. In addition, mRNA levels of the glucose transporters GLUT1, GLUT4, and insulin receptor substrate-1 were elevated by MDI stimulation, whereas SG dose-dependently inhibited the expression of these genes in differentiated adipocytes. SG also inhibited the phosphorylation of Akt (Ser473) at an early phase of MDI stimulation. Intracellular nitric oxide (NO) production and endothelial nitric oxide synthase mRNA levels were markedly decreased by MDI stimulation and recovered by SG treatment of adipocytes. Conclusion: Our results suggest that SG effectively inhibits adipocyte proliferation and differentiation through the downregulation of $PPAR{\gamma}$ and $C/EBP{\alpha}$, by suppressing Akt (Ser473) phosphorylation and enhancing NO production. These results provide strong evidence to support the development of SG for antiobesity treatment.

• Journal of Life Science
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• v.27 no.2
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• pp.155-163
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• 2017

Mori Folium, the leaf of Morus alba, is a traditional medicinal herb that shows various pharmacological activities such as antiinflammatory, antidiabetic, antimelanogenesis, antioxidant, antibacterial, antiallergic, and immunomodulatory activities. However, the mechanisms of their inhibitory effects on adipocyte differentiation and adipogenesis remain poorly understood. In the present study, we investigated the inhibition of adipocyte differentiation and adipogenesis by ethanol extracts of Mori Folium (EEMF) in 3T3-L1 preadipocytes. Treatment with EEMF suppressed the terminal differentiation of 3T3-L1 preadipocytes in a dose-dependent manner, as confirmed by a decrease in the lipid droplet number and lipid content through Oil Red O staining. EEMF significantly reduced the accumulation of cellular triglyceride, which is associated with a significant inhibition of pro-adipogenic transcription factors, including sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor-${\gamma}$ ($PPAR{\gamma}$), and CCAAT/enhancer-binding proteins ${\alpha}$ ($C/EBP{\alpha}$) and ${\beta}$ ($C/EBP{\beta}$). In addition, EEMF potentially downregulated the expression of adipocyte-specific genes, including adipocyte fatty acid binding protein (aP2) and leptin. Furthermore, EEMF treatment effectively increased the phosphorylation of the AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase (ACC); however, treatment with a potent inhibitor of AMPK, compound C, significantly restored the EEMF-induced inhibition of pro-adipogenic transcription factors and adipocyte-specific genes. These results together indicate that EEMF has preeminent effects on the inhibition of adipogenesis through the AMPK signaling pathway, and further studies will be needed to identify the active compounds in Mori Folium.